A. Field of Invention
The present invention relates to highly efficient lighting fixtures and methods that provide a light beam pattern suitable for illuminating pathways, walkways, and similar area lighting.
B. Problems in the Art
Many different types of light fixtures exist for the application of lighting pathways. Some of these include bollard, pagoda, or landscaping lights, and the like. These lights use different types of light sources ranging from incandescent to halogen to LEDs (light emitting diodes).
Most of the light sources use lamp wattages in the range of 20 watts or more. The lumen output per watt can be lower than desired, however, often in the range of 10-12 lumens per watt. Thus, the amount of light available on the surface to be lighted is limited unless the lamp wattage is increased, which would increase energy consumption. Therefore, energy efficiency is an issue.
Another problem in this field is that light from the fixture is generally not controlled or is poorly controlled. In other words, substantial light from the fixture does not usefully help light the defined target area. It either falls outside the target or is not useful to illuminate the area. This results in wasted light that does not contribute to the area to be illuminated, as well as creates a potential source of glare and spill light.
A common fixture design for a bollard light or pagoda light comprises a vertical post with the light source mounted near the top and surrounded by a transparent lens. An additional feature may include baffles to help direct the light downward. However, with these fixtures, typically more than 50 percent of the light is wasted as it is directed or travels away from the area to be illuminated. This wasted light not only consumes energy, but distracts from the visual appearance of the target (e.g., pathway) by illuminating areas outside of the target boundaries (e.g., sides of a pathway).
Glare or spill light from light that is poorly controlled is a concern for many lighting designers and viewers. When the light is not controlled or confined to the intended area to be illuminated, the fixture is not efficient. Inefficient fixtures must use higher wattage light sources to provide the required light needed at the target surface. This can increase the amount of glare viewed at the source. Even low wattage sources, such as LED's, can become a potential source of glare if the light source is in the viewer's line of sight. Thus, fixtures that control the light and reduce glare are important for this type application, and many others.
Another concern with many conventional types of these fixtures is maintenance cost. The operating life of the type of light source or lamp used may not be suitable for the application. Lights that operate for 10-12 hours a day will use around 4000 lamp hours per year. Types of lamps with lower lamp life spans will require replacement more often than sources that operate for long periods. For example, a lamp with 10,000 hour rated life will require replacement every 2.5 years, while a lamp with 50,000 hour rated life may not require replacement for 12.5 years. Less maintenance reduces the overall operating cost of the lighting system. However, many typical light fixtures for the above-described applications use lower rated life span lamps and are adapted for those types of lamps.
Therefore, many opportunities exist for improving the current state of lighting for pathways and similar or analogous areas or applications. It is the intention of this invention to solve or improve over such problems and deficiencies in the art.